A design method for transmission-line-based dual-band filters with completely independent passbands is demonstrated. The proposed method completely ignores the conventional restrictions imposed on the electrical lengths of the transmission lines. Consequently, each resonator is designed separately by the predetermined parameters. Unlike conventional dual-band filters, the susceptance slope parameters at two center frequencies do not need to be maintained in all sections. As a result, the proposed filter can be designed to not only have different bandwidths, but also different responses. In addition, tuning the J-inverter values increases the design’s flexibility and compensate the theoretical limitation. The experimental results for various filters verify the proposed method, including the outstanding passband insertion loss. For the first time, a filter with a Chebyshev response in one passband and a maximally flat time-delay response in the other is demonstrated in this work.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0016802).
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physics and Astronomy(all)
- Electrical and Electronic Engineering